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Old Jul 17, 2012, 12:40 AM
Jack of all master of none
splinterz25's Avatar
Baltimore MD USA
Joined Jan 2011
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Thanks J very good explanation I think I understand I'm going to try this for my p-38 cowls.

Bruce
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Old Jul 17, 2012, 04:02 AM
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J Morgan's Avatar
Chapel Hill, TN USA
Joined Apr 2001
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Bruce,
Probably the most important thing is the 3 coat of wax and 3 light coats PVA on the mold before you start. That is if you want to remove it.

J
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Old Jul 17, 2012, 11:49 AM
I don't do Normal
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Canada, NT, Yellowknife
Joined Dec 2011
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J for how often you build it may be worth wile to make a jig for this see sketch
Just drag it around the item keeping it flat, could be useful for other things to
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Old Jul 17, 2012, 02:50 PM
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Chapel Hill, TN USA
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That's a pretty good idea Pinky! I'll try that on the cowls. I'll have to make molds for those too.
Thanks!

J
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Old Jul 17, 2012, 04:39 PM
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Chapel Hill, TN USA
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So where were we? I'm in IL for a couple of days but can show some more progress done previously.
I waxed and PVA'ed the molds, 3 coats each. Then I primered the molds. Also had some blemishes that needed attention with bondo repair. These came when I missed an overlap joint on the initial layer of 3/4 oz and it left an impression.
Once they were all ready I started glassing. The nose was done with 3/4 oz first because of it's tight weave. that leaves a smooth surface on the outside of the part.
Heavier layers were then laid on. Same process with the doors.
Once done, in the storage room since it was about 95 degrees so it would cure out well.
Next we'll trim and pul them to see what we have.

J
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Old Jul 17, 2012, 04:54 PM
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Joined Feb 2010
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I said it before and ill say it again, someday I will have skills like you lol Hopefully
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Old Jul 17, 2012, 06:30 PM
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Crystal River Fl.
Joined Jul 2008
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Looks really good John. Hope your trip goes well. W
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Old Jul 17, 2012, 06:39 PM
Jack of all master of none
splinterz25's Avatar
Baltimore MD USA
Joined Jan 2011
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WOW J... really cool thanks for taking the time to show us how you make two part fiberglass molds! I like pinky_d_brains idea w/ the triangle also going to go get some more supplies and start on my p-38 cowls.
There not just smooth sides like these but if I don't go to deep w/ the recess on the front they should still come free and this way only have to carve one plug!

Thanks again,

Bruce
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Old Jul 18, 2012, 07:43 AM
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Chapel Hill, TN USA
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Thanks guys, hope someone is learning along with me.

So once cured you trim the excess glass. I use scissors to trim away as much as possible and then a flat snap off blade to trim close as possible to the mold surface.
If you encounter a really tough place where the blade just can't cut then I go to a Dremel thin diamond cut off wheel to cut close to the mold edge. Finally a sanding block to smooth up the edge and making sure it is flush all along the mold surface. Once that is done you simply pop the pieces out of the mold.
Mine came out easily thanks to the wax and PVA. The more parts you make the more the molds get seasoned and they release easier with each layup. Of course you still ned to wax and PVA them each time.
I did have a little problem with my primer "crazing" in a few places, not sure what caused it. Possibly a little too much heat in storage area when it was curing?
Any blemishes or primer problems are easy to fix with wet sanding and then repainting.
I had to do that to the seam on the nose cone where the two molds meet plus I had a small depression in one edge of the mold( that was a void when I made the mold), simple fix.
So I have both sets of nose cones and doors done, when I get back I just need to pul the second set. I left them curing when I took off for ILL. I will be leaving for home this afternoon so hope to get back on the build tomorrow.
I also sent the canopy mold off to Sparky for him to work his magic and save my butt!

J
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Old Jul 18, 2012, 09:24 AM
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rawy's Avatar
swiss watch makers area
Joined Dec 2002
812 Posts
Thank You J for the explanation on the canopy techniques,

there's loads to learn from watching your builds, thanks for sharing

Walter
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Old Jul 18, 2012, 11:53 AM
No Hangar Queens!
Maryland
Joined May 2009
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Quote:
Originally Posted by J Morgan View Post
I used 80 grit sandpaper and sanded all the bulkhead areas. Then I used med CA to glue them all in. Epoxy doesn't want stick to cured epoxy but CA loves it. I'll probably back it up with a smear of Gorilla glue just for insurance.

J
Getting back to your method for gluing bulkheads it occurred to me that over at another forum I picked up the use of Loctite Hysol epoxies. One guy used it almost the way you use gorilla glue. It seemed to stick to anything. The 80 grit sanding seems like a no-brainer for me as it would increase grabbing area for any glue rather than a flat surface. At this size the weight savings debate over glue types I think becomes only academic. Might want to give it a try if you come across some.
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Old Jul 18, 2012, 02:03 PM
Now in TN!
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Chapel Hill, TN USA
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Quote:
Originally Posted by Willsonman View Post
Getting back to your method for gluing bulkheads it occurred to me that over at another forum I picked up the use of Loctite Hysol epoxies. One guy used it almost the way you use gorilla glue. It seemed to stick to anything. The 80 grit sanding seems like a no-brainer for me as it would increase grabbing area for any glue rather than a flat surface. At this size the weight savings debate over glue types I think becomes only academic. Might want to give it a try if you come across some.

I'll Google that and check it out. Always happy to try new things. Thanks.

J
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Old Jul 18, 2012, 06:35 PM
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Joined Mar 2000
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Just ran across this. Another fun thread by the "Man" and "friends" Very nice, I look forward to following along in spirit. Thanks John! I have only 5 pages to catch up on, I feel like I barely have anything to do here!
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Old Jul 18, 2012, 09:53 PM
Now in TN!
J Morgan's Avatar
Chapel Hill, TN USA
Joined Apr 2001
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Thanks Eddie,
Nice to hear from you. Hope all is well. I got back home tonight and plan on getting some serious work done through the weekend. Looks like my time is going to be pinched next week so I do want to make some progress. Oct is not that far away.
Wing cores from my friend and National Balsa order are scheduled to be delivered tomorrow so it's not like I have any excuses.

J
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Old Jul 19, 2012, 04:13 PM
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Chapel Hill, TN USA
Joined Apr 2001
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Back to work. Been frantically trying to get Fuse # 2 ready to ship to my friend. Ply order came in today and I finished cutting all the bulkheads out, packed them in cardboard and so tomorrow it's a trip to Fedex to see if they have a HUGE box.
I trimmed the second nose cone and rear doors and pulled them from the molds. Nose cone is taped on the plug/skins and I will need to finish the doors before I can ship them.
My wing ocres came in from "friend" today too. Also the power system, props had come in about two weeks ago. Props are Biela 16x8 4 bladers from TroyBilt Models. They're pretty pricey at $81 each but are factory balanced and look killer! I'm using the same Turnigy SKE-5055-430KV motor that I used in the A-1 build. So I should get about 3000 watts on 6s with these props. Using the Turnigy 80A HV escs too.
Back to work on the doors now, more later.

J
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